lin-36, a Class B Synthetic Multivulva Gene, Encodes a Novel Protein Jeffrey H. Thomas and H. Robert Horvitz, HHMI, Dept. Biology, MIT, Cambridge, MA 02139, USA
It is an honor and a great pleasure to introduce Dr. Robert Horvitz to you as the 1998 recipient of the Alfred Sloan Prize of the General Motors Cancer Research Foundation. Let me begin by telling you a little bit about Bob's
The original version of this article [1] unfortunately contained a mistake. The author list contained a spelling error for the author Hannah V. McCue. The original article has been corrected for this error. The corrected author list is given below:Xi Chen, Hannah V. McCue, Shi Quan Wong, Sudhanva S. Kashyap, Brian C. Kraemer, Jeff W. Barclay, Robert D. Burgoyne and Alan Morgan
Metal ions are essential for life, with ~30% of all proteins being metalloproteins. The metallome (the metal complement of cells and tissues with associated proteins and transport systems) plays a critical role in many fundamental biological processes. Metal ion cofactors enable electron transfer reactions, providing catalytic potential as well as having significant effects on protein stability. Redox active transition metals (like Fe and Cu) are intrinsically involved in the generation of free radicals and highly reactive oxygen species (ROS). ROS have required roles as secondary messengers in cellular signal transduction and innate immunity. However, free radicals can also damage cellular macromolecules and ultimately impair function. There has been much interest in oxidative stress as a contributor to pathogenesis of many diseases. However, despite the fact that metal-mediated catalysis is the origin of most oxidative stress, remarkably little work has focused on metals. Until now the means to visualize and characterize metals in biology have been lacking. Furthermore, assessing the elemental composition of complex structures, such as cells and organelles, without destroying the intricate distribution has been a significant challenge. Developing analytical technologies partnered with an appropriate model system, like C. elegans, offers an ideal means to study the eukaryotic metallome. X-ray fluorescence microscopy (XFM) is well suited for investigating elemental distributions within biological specimens. Using XFM imaging we have mapped elements (Sulfur to Zinc, 16<Z<30) at ~1 mm resolution in adult C. elegans. Subsequent tomographic analysis has allowed identification of features not readily discernible in 2-D. To compliment these spatial data we have begun to apply a metal-based approach to systematically characterize and identify the native metal-protein complexes of C. elegans. We have combined native size exclusion chromatography (SEC) with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) to characterize and identify protein-metal complexes.
For the first time, scientists have the nearly complete genetic instructions for an animal that, like humans, has a nervous system, digests food, and reproduces sexually. The 97-million-base genome of the tiny roundworm Caenorhabditis elegans was deciphered by an international team led by Robert Waterston and John Sulston. The work was reported in a special issue of the journal Science (December 11, 1998) that featured six articles describing the history and significance of the accomplishment and some early sequence-analysis results.
Historically, peptidergic substances (in the form of neurosecretions) were linked to moulting in nematodes. More recently, there has been a renewal of interest in nematode neurobiology, initially triggered by studies demonstrating the localization of peptide immunoreactivities to the nervous system. Here, David Brownlee, Ian Fairweather, Lindy Holden-Dye and Robert Walker will review progress on the isolation of nematode neuropeptides and efforts to unravel their physiological actions and inactivation mechanisms. Future avenues for research are suggested and the potential exploitation of peptidergic pathways in future therapeutic strategies
Within the past few years researchers have finally begun to be able to peer inside a hitherto impenetrable black box, namely, the development of complex organisms. The genes that control the commitment of embryonic cells to specific fates are now being found and characterized. A case in point is reported in this issue of Science (p. 409). Victor Ambros of Harvard University and H. Robert Horvitz of Massachusetts Institute of Technology have identified genes that affect the timing of developmental events in the roundworm Caenorhabditis elegans.
One of the hallmarks of Alzheimer's disease is the cerebral deposition of plaques composed of Amyloid-beta (Ab) peptide. Human Ab (e.g. in brain, CFS or plasma) is not found as a single species, but rather as diverse mixtures of various modified and truncated forms. Caenorhabditis elegans offers a simplified in vivo system in which to examine Ab accumulation, including sub-cellular localization, and toxicity. We determined that an earlier model of Ab expression in C. elegans accumulates Ab3-42 due to mis-cleavage of a synthetic signal peptide. To achieve correct signal peptide cleavage we inserted an extra Asp-Ala (DA) N-terminal to the hu-Ab sequence in the transgene construct The molecular identity of the Ab expressed was then determined via complimentary techniques. Using immunocapture and electrospray ionization mass spectrometry (ESI-MS) we determined the mono-isotopic molecular weight of the expressed Ab as 4511.2586 Da with an error of 2.5 ppm. This mass is consistent with full length Ab1-42 (expected mass 4511.2697 Da). The Ab1-42 is expressed in body wall muscle cells, where it aggregates and results in severe, and fully penetrant, age progressive-paralysis. The in vivo accumulation of Ab1-42 also stains positive for amyloid dyes, consistent with in vivo fibril formation. This C. elegans model of full length Ab expression can now be adopted to study underlying toxic mechanism(s) of Ab1-42.
The overwhelming complexity of higher organisms can make it hard to know where to begin to understand them. The three scientists who share this year's Nobel prize for physiology or medicine, Sydney Brenner (Salk Institute, La Jolla, CA, USA), John Sulston (Wellcome Trust Sanger Institute, Hinxton, UK), and Robert Horvitz (Massachusetts Institute of Technology, Boston, MA, USA), all chose to study a far simpler organisms - the nematode worm Caenorhabditis elegans. Although multicellular, this organism reproduces rapidly and is transparent, so that each developmental stage can be seen clearly without the need for dissection.